CppCoreGuidelines Per.19 以可推断的方式访问内存

int matrix[rows][cols];

// bad
for (int c = 0; c < cols; ++c)
    for (int r = 0; r < rows; ++r)
        sum += matrix[r][c];

// good
for (int r = 0; r < rows; ++r)
    for (int c = 0; c < cols; ++c)
        sum += matrix[r][c];